It is second Asian Tour title of the season for Kapur, who fired five birdies against one bogey to stay three strokes clear off a pack of fellow Indians, including Ajeetesh Sandhu (65), Sudhir Sharma (69) and Chirag Kumar (64).
Kapur had won the Yeangder Heritage in April and finished second at the Thailand Open this season. He had won his first Asian tour title in 2005 at the Volvo Masters of Asia.
Others to finish tied second are Karandeep Kochhar (66), SSP Chawrasia (69) and Om Prakash Chouhan (69).
"I am lost for words. You dream about winning but I never got so far in my career so I never prepared a speech in my life," said Kapur.
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"When I won the Volvo masters it was a spring board for me and then there was a long gap and I didnt know if I will be able to win but Yeangder win gave me the belief that I can win again and winning here after all these years is really special. All wins have their own place in my heart.
First-round leader, Sandhu, who has been in rampaging form in the last three months with a T-3 at Take Solutions in Bengaluru, followed by a win in Taiwan and a win on the Japan Challenge Tour, sizzled with eight birdies and a bogey to provide a charge on the fourth day.
Chawrasia, who has won three different Asian Tour events here the 2008 Emaar-MGF, the 2014 Panasonic Open India and the 2015 Hero Indian Open at the DGC, also signed off at 274 after scoring five birdies and two bogeys.
Chiragh, who won the 2015 edition of the event and also was a runners-up at Hero Indian Open in 2011, fired nine birdies and a bogey in his sensational eight-under 64, while Chouhan carded three birdies, including picking a stroke at the last hole, to also break into the second place.
"When I walked with a three stroke lead at the 18th and hit the second shot down the fairway, there was a big sigh of relief inside me. I knew I can allow a little celebration now, said the 35-year-old, who had won his first Asian tour title in 2005 at the Volvo Masters of Asia.